This invention relates to a fluid filter element and method of forming the same.
Fluid filter elements are well known and are widely used in fluid filters for varying areas of use, including hydrodynamic machines and air-conditioning engineering. Their meander-shaped or zig-zag structure provides a substantially increased filter area, in relation to a fixed afflux flow cross-section. In order to fix the fold walls of such a structure relative to each and to support them with respect to each other, various different kinds of design configurations have been developed. Filters with depressions which are embossed into the flat filter material and which, when the material is folded, bear against each other and support each other are known.
In the case of earlier fluid filter elements of that kind, the embossings of the fold walls were simply laid against each other when executing the folding operation and the filter element, which was finished as a kind of “fold pack” which was externally fixed by being clamped in a box or frame. While such particularly simple fluid filter elements certainly operate satisfactorily at the beginning of their period of use and in areas of use which do not involve fluctuating pressure loadings worth mentioning, critical stability problems are found to occur in relation to certain degrees of filling with deposited dust particles, or dust loading, and in particular when used in relation to fluid-dynamic machines.
In order to resolve many of the above problems, U.S. Pat. No. 6,685,833 assigned to LPD technologies discloses a filter element comprising an embossed flat filter material which is folded so as to define a plurality of substantially adjacent walls, each wall having an embossing comprising a first embossing portion which extends from one side of said wall and a second embossing portion which is adjacent to said first embossing portion and which extends from the other side of said wall, and an adhesive connecting adjacent embossings of adjacent walls. The adhesive preferably has a substantially constant height. U.S. Pat. No. 6,685,833 is hereby incorporated by reference in its entirety.